"Online betting" is the most expensive catchphrase for Irish advertisers to be associated with on Google, according to research prepared for the Sunday Independent.

Woflgang Digital, a digital-marketing agency which handles 2pc of all of Ireland's e-commerce business, says that advertisers will pay more to appear in search results for "online betting" than almost anything else - some €40.69 per click.

The average cost per click in Ireland is €0.38, it said.

The analysis applies to Google's AdWords system, which generates the vast majority of revenue collected by Google, the largest company in the world.

AdWords takes 14pc of all global spending on advertising.

A high cost per click indicates advertisers are confident that they will earn a lot of money for each click that becomes a customer - which generally is only around 1pc.

"Online stock broker" was found to be the second-most expensive Google search phrase for Irish advertisers to be associated with, at €32.21 per click.

"Personal injury claim" came in at €22.44, while "life insurance quotes" clocked in at €11.74 and "mortgage deals" costs €11.32 per click.

"Google's AdWords system is relatively complicated to explain but, in a nutshell, advertisers decide what keywords they want to advertise on and they bid how much they are prepared to pay for a click from somebody searching for that word.

"It's pay-per-click advertising, so the advertiser only accrues a cost if a potential customers clicks on the ad and visits their website," said Wolfgang Digital Chief Executive Alan Coleman.

"The more valuable a product is, the more advertisers will pay for clicks. A rough rule of thumb is that 1pc of website traffic becomes a customer.

"So the cost of 100 clicks needs to leave room for the transaction to be profitable. Take a retailer selling designer sunglasses for €200, of which €50 is profit.

"The cost per click for 'designer sunglasses' searches is €0.20. So at a 1pc conversion rate, the cost of winning the sale is €20, leaving €30 profit.

"It's important to note that Google rewards effective and creative advertising by increasing its ranking and lowering its 'cost per click'. Having a strong quality score means a smart advertiser can rank higher and pay less than their competition."

A Google spokesperson added that the value of catchphrases changes regularly based on seasonality or what is in demand at a specific time.